1. Field of the Invention
The present invention relates to an image processing apparatus, a printing system, an image data format selecting method, a program, and a storage medium, and particularly relates to an image processing apparatus, a printing system, and an image data format selecting method that are suitable for applying to storing in a recording medium electronic information of images picked-up by a digital still camera that records static images, a digital video camera, or the like and printing out the electronic information by a printer through the recording medium, and a program for implementing the method, and a storage medium storing the program.
2. Description of the Related Art
Conventionally, some thermal transfer line printers use thermo-sensitive paper sheets as print sheets, selectively drive a plurality of heating elements arranged in the main scanning direction, and feed the sheets in the subscanning direction to print images in dot lines on the sheets.
In recent years, with the advancement of input devices, as the image input side, which handle images, such as digital cameras, digital video cameras, and scanners, thermal transfer printers as printing units have also come to be focused on. This is because, while inkjet printers only allow a digital choice as to whether to eject liquid drips and eject small liquid drips to sheets to obtain apparent resolution and gradation by a method such as error diffusion, thermal transfer printers can easily change the value of controllable heat for a single pixel, which makes it possible to obtain various graduations for a single pixel so that images which are smoother and with higher image quality compared to inkjet printers can be obtained. Further, with the improvement of the performance of thermal heads of thermal transfer printers and the performance of sheet materials, image prints which look as good as silver-salt photographs in finished quality have come to be obtainable. Consequently, thermal transfer printers have come to be focused on particularly as printers for natural images with the advancement of recent digital cameras.
Therefore, there have been proposed systems in which a printer device, as described above, and an image pickup apparatus such as a digital camera or a digital video camera are directly connected to each other or constructed in one body, whereby image information of picked-up images is printed not through an apparatus such as a computer that processes image information.
A printing system that directly connects a digital camera and a printer device will be described in detail. Images picked up by the digital camera are once stored in a recording medium provided in the digital camera. To print out the images from the printer device, a user directly connects the digital camera and the printer with a dedicated cable. Then, the user displays the images stored in the recording medium on a display unit of the digital camera and selects an image that the user intends to print. Needless to say, on this occasion, an operating element provided in the digital camera is used to select the image. When the user has selected the image to be printed, the user pushes a print key, which is allocated to the operating element of the digital camera. Thus, image processing for prints is performed in the digital camera. When image processing in the digital camera has been completed, data for printing is transmitted to the printer device, and then the printer device prints out the received data for printing.
In the above-described printing system, the user only needs to operate the operating element of the digital camera a few times to print out the data by the printer device, which facilitates photographic printing and is greatly convenient.
Due to intended applications of digital cameras, digital camera generally have a JPG chip for compressing the data of picked-up images into a JPG (Joint Photographic Experts Group) file or expanding the JPG file into image data to reproduce the same, and an IC chip having a resizing function of adjusting picked-up images data to desired sizes. Effective use of the hardware resources of the digital camera to generate print data not only greatly shortens the processing time compared to the case of implementing the JPG expansion and the resizing function by software processing, but also enables forming resources required of the entire printing system of a minimum number of resources, which results in lower costs.
However, the above-described prior art has the following problem. The implementation of image processing of print data in the inside of the digital camera as in the printing system of the above-described prior art has an advantage of effective utilization of hardware blocks suitable for image processing for generating print data, but it has also a disadvantage that the implementation is restricted by other hardware blocks included in the digital camera. Specifically, image processing for generating print data must be performed within a limited size of a working memory provided in the digital camera, which causes shortage of the working memory capacity in the digital camera when the size of print data is large.